AT&T’s on-net business fiber dominance continues

AT&T’s on-net business fiber reach remains the envy of the business communications service industry, and the fact that it has been able to hold onto the top spot on Vertical Systems Group’s Fiber Lit Buildings LEADERBOARD for the tenth year is a testament to the company’s fiber-centric approach. 

The service provider’s on-net fiber reach has been achieved through its own aggressive build-out combined with acquisitions,  

During the past year, VSG noted that the “service provider has steadily expanded its installed base of fiber-lit buildings across the U.S.”

Evidence of AT&T’s dominant foothold in on-net fiber was reflected in the telco’s first-quarter results. AT&T’s Business Fiber and advanced connectivity revenues rose 7.2 percent to $1.9 billion, while its Business transitional and other revenues declined 16.3% to $1.1 billion.  

The service provider saw its Advanced Connectivity business service revenue stabilize on a year-over-year basis for the first time, reflecting improved growth in fiber and 5G that is now offsetting declines in transitional services such as VPN.

“We are seeing strong growth in our business fiber and advanced connectivity service revenues, which include business fixed wireless and value-added services,” said Pascal Desroches, CFO and VP at AT&T, during the first quarter earnings call. “In the quarter, these revenues grew 7.2% year-over-year, which is consistent with the trend last quarter and improved from mid-single-digit growth a year ago.”

Closely following AT&T is fellow telco Verizon.

Verizon, which ranked fourth on VSG’s Ethernet LEADERBOARD, is expanding its on-net fiber footprint to support a host of enterprise and wholesale services for data center providers.    

“On the commercial side, we are in quite deep discussions right now with hyperscalers, with alternative cloud providers, large enterprises to integrate our Fiber, both dark and lit, and our 5G assets to support their AI infrastructure efforts,” said Dan Schulman, CEO of Verizon. “And that can include data center connectivity, ability to help them with their training and inference.”

On-net buildings rise

In 2025, it was clear that service providers continued to enhance their on-net fiber reach through organic efforts and through acquisitions of other fiber providers.

VSG noted that the installed base of fiber-lit commercial buildings and Data Centers reached nearly two million sites. The 2025 LEADERBOARD expanded to 13 companies that have achieved the threshold of 25,000 or more fiber-lit buildings.

Joining AT&T and Verizon on the 2025 on-net fiber LEADERBOARD were 11 other companies, including Spectrum Business, Comcast Business, Lumen, Cox Business, Zayo, Crown Castle, Frontier, Uniti, Breezeline, Brightspeed, and Segra.

Three fiber providers advance to the LEADERBOARD from the Challenge Tier: Uniti (including Windstream), Brightspeed and Segra (including UPN).

VSG said the total of 13 retail and wholesale fiber providers qualify for the year-end 2025 benchmark based on a threshold of 25,000 or more on-net U.S. fiber-lit sites, including commercial buildings and Data Centers.

While more providers were added to the 2025 LEADERBOARD, the rankings for the top nine providers remain unchanged.

“U.S. installations of commercial fiber circuits and lit buildings increased in 2025 as providers focused on higher speed offerings. Top fiber providers are actively expanding buildouts to meet demand for lower latency, higher bandwidth edge computing applications driven by AI,” said Rosemary Cochran, principal of Vertical Systems Group. “The number of lit fiber buildings increased across every building size segment during the past year. Currently, greater than 80% of large and medium-sized buildings are fiber-lit.”

Like the top rankings, seven companies attained a 2025 Challenge Tier citation: Altafiber, Conterra Networks, Everstream, Fidium, FirstLight, Great Plains Communications, and Lightpath.

Each of these providers qualifies for the 2025 Challenge Tier, with between 5,000 and 24,999 U.S. fiber-lit commercial sites.

The M&A effect

Another key factor that will impact the on-net fiber rankings this year is that a group of LEADERBOARD providers has already completed or is planning mergers.

In 2026, AT&T acquired Lumen’s Mass Markets fiber business, and Verizon acquired Frontier.

Meanwhile, Zayo closed its acquisition of Crown Castle’s fiber solutions assets, while the Charter/Cox deal is expected to close this year.

By acquiring Crown Castle’s fiber solutions assets, Zayo added approximately 90,000 route miles and 40,000 on-net enterprise locations to its network.

The acquisition will benefit both its existing and new customers. Existing Zayo customers will have more on-net access, route diversity, and capacity in key markets. And for new enterprise customers, it adds the scale of Zayo’s national backbone, enabling greater access into the data centers, cloud platforms, and AI ecosystems where bandwidth demand is growing fastest.

Charter/Spectrum’s proposed acquisition of Cox could also affect the cable operator’s ability to scale its business service presence to more business buildings.

“In addition to benefiting from better mobile and video products, the Cox communities will benefit from lower promotional and retail pricing, sales channel expansion, including field sales and stores, and our very complementary B2B capabilities, which will help accelerate growth in both the Cox and Spectrum business,” said Stefan Anninger, Senior Vice President, Investor Relations at Charter.

VSG said the impact of these deals “will be reflected in our next analysis.”

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